Partial Discharge Pulse Extraction and Interference Suppression Under Repetitive Pulse Excitation Using Time-Reassigned Multisynchrosqueezing Transform

High-frequency repetitive pulse excitation is prone to induce partial discharge (PD) of power equipment, resulting in premature insulation failure. PD detection plays an important role in insulation condition monitoring. However, the severe switching electromagnetic interference (EMI) pulses of power electronic devices and the concentrated PD behavior pose difficulties for accurate PD detection. A novel method for detecting weak signals of PD pulses with EMI based on time-reassigned multisynchrosqueezing transform (TMSST) and similarity distance measurement is proposed in this article. First, the TMSST method is employed to reassign the signal energy distribution in the time-frequency domain, which can significantly enhance the time-frequency resolution of pulse signals. Then, the density-based spatial clustering of applications with noise (DBSCAN) clustering method based on the time-frequency energy distribution is employed to detect individual pulse signals. A mask-filtering technique is utilized to filter the noise and reconstruct the pulse signals. Next, the similarity of each extracted pulse signal is measured using the complexity-invariant distance (CID) criterion to identify and remove the EMI pulses. Finally, the performance of the proposed method is verified through simulated data and experimental tests under repetitive pulse excitation. The results demonstrate that the proposed method in this article exhibits good performance in handling weak PD pulse signals and effectively eliminating the switching EMI pulse.